Applied Mechanics and Materials Vols. 295-298

Abstract: It is considered that discussion on adaptability of sequence stratigraphy in fluvial sedimentation is significant for oil exploration. As the main controlling factor is the sea-level fluctuations in the coastal river system, Exxon sequence stratigraphy can be applied to divide the sequences into: lowstand, transgressive and highstand systems tracts. And in the inland fluvial system, the application of low- and high-accommodation systems tracts may keep more coincident with the actual stratigraphic record. From the Exxon stratigraphy to low- and high-accommodation systems tracts, each model will be of great value in the petroleum exploration because of the lateral phase transition raised and the vertical phase transition predicted. However, controlled by many allogenic processes, fluvial strata still shows many problems in which the patterns can not be clearly explained. Thus, fluvial sequence stratigraphy needs to be further developed. Researching on various models of fluvial facies sequence stratigraphy in the development process will bring the important theoretical and practical value to the oil reservoir exploration.

Abstract: Based on recent exploration of Carboniferous volcanic of Kelameili gas field in Junggar Basin, northern Xinjiang, a series of technology have been formed to identify lithology and lithofacies of complex ancient volcanic. Carboniferous volcanic types in this gas field are complicated and diversified; the identical lithology is different in texture, structure and component, as well as relevant typical characteristics, making it hard to identify lithology and lithofacies. According to the observation from 16 wells in Ludong area with 92 tubes of cores, 235 typical pictures and 631 sections, the article denominated the volcanic lithology. The lithologic and electric relationship of volcanic were built by the data of cores, sections and calibration logging, which laid a foundation for building the volcanic lithologic-electric plate. Density-gamma crossplot, acoustic-gamma crossplot and resistivity-gamma crossplot in Ludong area are made, and several complex volcanic types are identified, such as rhyolites, basalts, basaltic volcanic breccias, andesites and andesitic firing breccias. Through logging-seism-combined identification technology of volcanic lithofacies, the seismic properties of different volcanic types are distinguished, finally the distribution of explosive facies, outflow facies and volcanic sendimentary facies are divided both on plane and profile.

Abstract: Mercury injection capillary pressures (MICP) on the coal samples were measured with a variety of pressure regimes. The goal was to compare the effects of different pressure regimes for determining the compressibility of the coal. The two samples were taken from Northeast China. MICP profiles up to 204 MPa were measured on two different crushed samples of the same size. Three linear regimes namely, at 10-40 MPa, 40-100 MPa and P>100 Mpa are defined, corresponding with the diameters of mesopore and microspore. The standard deviations of the compressibility values were less than 20%. The results from the present study suggest that the different pressure regimes affect the compressibility values slightly.

Abstract: In order to clarify some kinds of geological conditions on the hydrocarbon accumulation process, this paper analyses the main factors controlling oil-gas enrichment regularities of Putaohua oil layer in Chaochang region of Daqing city, which conclude tectonics, sedimentary characteristics, oil source condition and the mutual relationship between of them. The results show that the organic abundance of hydrocarbon source rocks of Qing1 section control oil and gas distribution range. The configuring relationships of oil-source fault and reservoir sand body control oil and gas migration. The configuring relationship of sedimentary micro-facies types and structures controls oil and gas distribution. On the basis of these studies, oil and gas accumulation mode in Putaohua reservoir are summarized in Chaochang region. There are two accumulation models: nearby accumulation mode in northwest and updip accumulation mode in southeast.

Abstract: Overpressure is often encountered in the Jurassic tight and the overpressure is closely associated with gas generation. The pressure transfer from the over-pressurized mudstones to adjacent tight sandstones might occur through overpressure induced-fractures. The fine-grained coal containing Jurassic sandstone is sensitive to compaction, and the porosity decreases dramatically with the increase of overlying load. As gas migrates into the tight sandstones, it must overcome the capillary pressure which is greater than the hydrostatic pressure. The gas charging pressure in the tight sandstone must be higher than the capillary pressure, resulting in an overpressure buildup within the tight sandstones. Gas shows, low permeability and strong diagenesis in the overpressure of the tight sandstone system have been observed. Additionally, capillary seals are identified as playing an important role in the mechanism of the overpressure formation in tight sandstone reservoirs. Overpressure might be a driving force to create induced fractures in the interval, which has applications for crossing-formation migration and gas accumulation.

Abstract: There are different understanding of long-standing and significant differences about the characteristic and age of the basement of Junggar Basin. And the existence of Precambrian crystalline basement and the nature of Paleozoic folded basement of the Junggar basin are under question. The research aims including the basin peripheral orogenic clastic zircon dating and the drilling samples. Those research playing a key role in rebuilding the tectonic framework, reconstructing the geological evolution of northern Xinjiang region; and provides the basis for geological research in the area of objective information, provides an important basis in the evolution of continental geology and dynamics; also available as a scientific theory and support to resource development, it is of great value in the exploration and evaluation of resources within the basin.

Abstract: To analyse the potential evaluation of shale gas resources and to know the resources of shale gas in Chongqing northeast, it is very important to research on the methods of shale gas resources potential evaluation in the application of Chongqing northeast. Based on the research of shale gas resources potential evaluation by comparing with the American, and combined with the characteristics of shale gas in Chongqing northeast and the thickness, density, buried depth, TOC, Ro, organic types, conditions of cap rock and reservoir, using abundance analogy method, volume method and Delphi method in this area to forecast preliminarily the shale gas resources in Chongqing northeast. The results show that there are rich in shale gas resources of Chongqing northeast and have broad prospect for exploration.

Abstract: The existence of abundant hydrocarbon has been discovered in the Yakela Fault-convex, Tarim Basin, after reconstructing and superimposing for several periods. Through interpretation of 3D seismic data up to date, combined with the circumferential field geology, after comprehensively analyzing the characteristics of development on hydrocarbon migration passages and its relationship with hydrocarbon accumulation, this paper holds that it is divided into fault type, unconformity type and carrier bed type in the Yakela fault-convex. The unconformities and the carrier beds are the main lateral migration passage of gas and oil for long distance. The faults are the main vertical migration pathway of hydrocarbon, and the hydrocarbon can arrive at any strata with fault. It is significant to know the hydrocarbon migration pathways in the study area for exploration in future.

Abstract: In the past decade, no geological research has been done in Zhaoyuan-Taipingchuan area. The research and understanding on the area is still in 1990s and far away from meeting the needs of exploration. What has to be done now is to further analyze the accumulation factors from points-view of tectonic characteristics, tectonic division and tectonic controlling over sedimentation. Deeper understanding on fault-lithology and lithology hydrocarbon reservoir is especially important for favorable hydrocarbon zone evaluation and target zone selection. Taking these into account, accumulation factors are briefly introduced in the article.

Abstract: The classification of flow units is the deep study of reservoir heterogeneity. In this paper we use a part of some oilfield as an example. Vertical flow units subdivision is up to the standard of single sand layer, which is the delicate reservoir anatomy. We use the related parameters and core data to obtain the quantitative standard of horizontal flow unit classification of no-coring well by the colligation coefficient method. Flow units distribution is consistent with distribution of sedimentary facies, it changes only in partial zone. Flow units distribution basically reflects the variation of sedimentary facies, it shows the plane macroscopic heterogeneity of reservoir.